1. Field of the Invention
The present invention relates to a cable reel of an electric signal transmission apparatus for an electrical connection between a stationary matter and a movable matter by using a tape-shaped cable and particularly to a cable reel suitable for use in a steering device of a vehicle.
2. Description of the Related Art
In the case where signal transmission is performed between the handle side of a car and the car body side thereof, such a device as shown in FIG. 2 is used. That is, a tape-shaped cable is spirally accommodated in a housing having an inner cylinder and an outer cylinder so that the rotation of a handle is absorbed by tightening and loosening of the winding of the tape-shaped cable.
As shown in FIG. 2, a conventional cable reel includes a housing having an inner cylinder 1, outer cylinder 2 and holder 12, and a tape-shaped cable 5 which is spirally wound and housed in the housing. The inner top end portion of the tape-shaped cable 5 is pulled out from the housing through a hole 10 of the inner cylinder 1 to the outside of the housing. Then, the tape-shaped cable is assembled to the inner cylinder 1, and the outer top end portion of the tape-shaped cable 5 is pulled out from the housing through a hole 11 of the outer cylinder 2 so that a grasping portion 9 is pulled out from the housing through the hole 11. After the grasping portion 9 is supported around the hole 11, the inner cylinder 1 and outer cylinder 2 are rotatably connected to each other. Further, connecters are fixed to both end portions of the tape-shaped cable 5 being pulled out from the housing so that the inner and outer end portion sides are connected to a control unit and a inflator side, respectively. Accordingly, the tape-shaped cable 5 in the housing makes the electrical connection between the control unit and inflator be possible.
In the apparatus of FIG. 2, there has been a problem in that the structure of the outer cylinder 2 is so complicated that it is difficult to form the outer cylinder 2 through injection molding and the metal mold is quite complicated and expensive. Further, in assembling the cable reel, it is necessary that a tape-shaped cable be passed through holes 10 and 11 formed through the inner and outer cylinders respectively, and that respective end grasping portions 8 and 9 provided on the tape-shaped cable 5 in advance are fixed on the inner and outer cylinders by using a lock mechanism. The work for passing a tape-shaped cable 5 through the respective holes 10 and 11 of the inner and outer cylinders 1 and 2 as described above is troublesome, and the assembly cannot be automatized so long as such work is required.